Suppression of noise from small air pumps, which can be used for example in such widely varying applications as health care devices and household aquaria, has long been desirable because even relatively low level acoustical emissions in a home or hospital environment can be disturbing. Prior devices have proposed a variety of solutions to the problem of excessive noise and vibration with varying degrees of success.
U.S. Pat. No. 3,266,716 to Tussey discloses an air pump actuating device which reduces chatter by displacing the armature away from the electromagnet during increased loading. The device is housed in a cylindrical shell.
U.S. Pat. No. 3,371,852 to Holt discloses an air pump including leaf springs to support the shaft and eliminate problems associated with horizontal displacement of the shaft. The pump also includes an outlet control device.
U.S. Pat. No. 3,669,573 to Levensohn discloses a vibrator pump mounted to a base, preferably made of wood, having a natural frequency of vibration below the excitation frequency of the pump.
U.S. Pat. No. 3,989,415 to Van-Hee et al. discloses a silencing housing for a machine plant having a primary chamber enclosing the machine plant and having an air inlet, and a secondary chamber having both an air inlet and an air outlet to reduce air flow noise.